Mass extinctions have radically influenced the history of life on Earth. Will we eventually succumb to such a catastrophe? Perhaps, but, in her new book Scatter, Adapt, and Remember, io9 editor in chief Annalee Newitz argues that we can avoid calamity through technological innovation and sifting clues from Deep Time about what allowed some organisms to persist in the face of destruction. One such creature is Lystrosaurus – a tubby, tusked cousin of ours whose kind lived through the worst mass extinction pulse of all time. In this guest essay, Annalee pays tribute to the mascot of survival.

Lystrosaurus: The Most Humble Badass of the Triassic

By Annalee Newitz

One of the greatest survivors in all of Earth’s history was a humble creature named Lystrosaurus. It was a dog-sized animal whose peculiar lineage evolved about 270 million years ago, and looked like a cross between a pig and a lizard. Snub-faced and splay-legged, it was a burrower with powerful front legs who probably dug its own den every night. And somehow, it managed to survive the worst mass extinction the world has ever known.

About 250 million years ago, at the close of the Permian period, an enormous volcano called an igneous province started erupting in the region of the world that would one day be Siberia. At the time, this volcano was at the northern tip of a supercontinent called Pangaea that stretched from the north pole all the way down to the south. The eruption formed massive vents, rifts in the earth that released wave after wave of lava, along with billowing clouds of ash, carbon, and other toxins.

The Siberian igneous province laid waste to the environment for over a thousand years, ultimately releasing as much as to 43,000 gigatons of carbon into the atmosphere. It’s likely that the planet cooled down for a time, then heated up into a devastatingly profound greenhouse. At the same time, all that carbon caused ocean acidification. The resulting climate changes ultimately killed off 95 percent of all species on Earth.

Lystrosaurus was a therapsid, a group often described as the mammal-like reptile branch of the synapsids, a group that eventually evolved into mammals. Though Lystrosaurus‘ progeny died out, they were nevertheless part of a phylogenetic unit whose evolution continues today. So while they are not our direct ancestors, I like to think of these little guys playing a kind of avuncular role in humanity’s evolution.

They certainly had one thing in common with us: they tunneled underground to deal with disaster, just like Permian-era preppers. The shape of Lystrosaurus‘ skull suggests it was a burrower, while its barrel chest may have held lungs capable of pulling in plenty of oxygen even in dusty air, full of contaminants. Spending a lot of time underground is a good survival tactic in a world whose climate is going haywire. Underground food sources are less likely to be affected by airborne particles blocking the sunlight.

It’s also possible that Lystrosaurus‘ adaptation to underground life prepared it for a world whose atmosphere was full of dust and ash for centuries. Those big lungs may have been the perfect way to breathe as the Siberian volcano erupted.

Another way Lystrosaurus survived was simply by walking. A lot. Based on enormous number of fossils found by paleontologists over the past 150 years or so, it seems that Lystrosaurus was also a great wanderer. These splayfooted creatures managed to escape some of the worst effects of the Siberian igneous province by scuttling south. Lystrosaurus was good at locating new ecosystem niches in far-flung places. It speciated — evolving into at least three new species, possibly more — and adapted to the southern part of Pangaea, called Gondwana. They were so successful that at one point in the early Triassic, these synapsids were the single most common vertebrate on land.

Of course Lystrosaurus‘ survival may also have come down to luck. During the early Triassic period, food webs were in flux. According to California Academy of Sciences paleozoologist Peter Roopnarine, who has studied food webs of the period, many ecosystems were simply too unstable to remain intact over the long term. There may have been simply too many predators, including the fierce, toothy ancestors of alligators. And yet for some reason, none of these animals preyed on the herbivore Lystrosaurus. Possibly, at three feet long, Lystrosaurus was just slightly too large to be appealing as a meal.

With seemingly no natural predators, the ability to live underground, and an insatiable wanderlust, Lystrosaurus thrived during the horrific early millennia of the Triassic. These seemingly unstoppable animals watched as the world recovered from the worst mass extinction it had ever endured.

Today, Lystrosaurus is more than just a role model for preppers. It also helped transform the way we understand the Earth. Lystrosaurus fossils provided some of the most persuasive pieces of evidence for plate tectonics in the late 1960s, because their skeletons were found in diverse regions of the world, including Africa, China and Antarctica. This distribution of their remains could only be explained if the continents had once been connected, allowing these land animals to wander from one region to the other.

What is truly inspiring about these animals, though, is that they survived without being deadly warriors. They had no giant teeth nor armored plates for protection. Instead, they survived the early Triassic by adapting their behaviors to new environments, and living absolutely anywhere they could. If these weird lizard-pigs could make it through a mass extinction, there’s hope for humanity after all. Especially if there are no giant crocodiles trying to eat us.

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5 thoughts on “Lystrosaurus: The Most Humble Badass of the Triassic”

So what is basis for “no predators”? Has skeletal damage been compared with that for any other medium-size tetrapods ‘before the fall’? [After the end-of-Permian extinction, when they made up such a large fraction of biomass, there might have been few predators left, but they surely would have gone after Lystrosaurus.

On another note, read Peter Ward’s contention that the real sorting-out in terrestrial systems was low atmospheric oxygen — that mammaloids, barrel chested or not, had inferior respiratory systems compared to contemporary archosaurs…

Lystrosaurus was probably preyed on by early archosaurs (ancestors of crocodiles and the Dinosauria, including birds) as well as its more carnivorous synapsid relatives. IMHO this is a much better account of Lystrosaurus than can be found in her book, “Scatter, Adapt and Remember: How Humans Will Survive a Mass Extinction”, but would not recommend this book as a popular scientific treatment on mass extinctions. (For example, to my surprise there isn’t any discussion of the pioneering work done by the “Chicago” school of paleobiologists (the late Jack Sepkoski, David Raup, David Jablonski, Michael Foote and their colleagues) in statistically analyzing the fossil record in order to understand the timing and severity of mass extinctions and in how ecosystems recover in their aftermath. IMHO paleobiologists Peter Ward and Michael J. Benton, among others, have written much better books devoted to understanding mass extinctions; potential readers would be better off reading those books, not Newitz’s.

Early archosaurs (ancestors of crocodiles and the Dinosauria, including birds) and carnivorous synapsid relatives of Lystrosaurus probably preyed upon it. For these predators, Lystrosaurus might have been the “wildebeest” of the earliest Triassic. In fairness to Newitz she has written a far better account of Lystrosaurus than appears in her book, but for those who wish to understand mass extinctions, then they would be much better off reading paleobiologist Peter Ward and Michael J. Benton’s books.

This is a most engaging account of a fascinating animal. The one thing missing in several accounts of Lystrosaurus that I’ve read is … what eventually happened? Did they die out quickly or gradually, or did they evolve into successful descendants? And over what length of time?
The more I read of animals the more I see the human race as having so many ‘species’ within the race. Probably not a new thought, But I seem to see predators, herbivores, omnivores, scavengers, all sorts of types of humans who seem analogous to widely diverse species in the animal world. For instance Brian S’s mention of ‘giant alligators’ at the end of his piece makes me think of the top Hedge Fund Managers today.
Ron Thompson

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Ed Yong is an award-winning British science writer. Not Exactly Rocket Science is his hub for talking about the awe-inspiring, beautiful and quirky world of science to as many people as possible.
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